If I remember correctly (been a while since I played with Applescript) I think you could save a script and set up the UI so that you can launch it in the macOS UI (instead of firing up a Terminal.app and entering the command by hand)
No; if you give a shell script the .command extension (and make it executable), then you can double-click it in the Finder to open and run it in the Terminal application.
Might be something a more current macOS user would have to answer. I just remember doing this using a little applescript menu icon on the topbar.
edit: now that I think about it, I did use "bitbar" for a while which is actually a little bit more powerful still. I can't find it any more but this looks similar - https://github.com/matryer/xbar#get-started
